Electron beam control device

ABSTRACT

There is provided an electron beam control device which controls an electron beam for use, such as an electron microscope, an electron beam exposure device and the like wherein a track of an electron beam is not adversely influenced by the amount of magnetic variation occurring from surrounding influences. The electron beam control device which controls an electron beam for use, such as an electron microscope, an electron beam exposure device and the like wherein a magnetometric sensor for measuring an amount of magnetic variation which influences a track of the electron beam, occurring from surrounding influences, is provided.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an electron beam control device which controls an electron beam for use, such as an electron microscope, an electron beam exposure device and the like, and in particular to an electron beam control device where an adverse influence on a track of an electron beam, due to the amount of magnetic variation occurring from surrounding influences, does not occur.

[0003] 2. Description of the Related Art

[0004] Control of an electron beam such as a microscope and an electron beam exposure device using an electron beam is easily influenced by the surrounding magnetic variation. Particularly in case of an electron beam exposure device for preparation of a photomask, it is known that, with the increase in the density of the semiconductor device, with the proceeding miniaturization of the pattern of the photomask, in recent years, the influence upon the positional control of an electron beam is a serious problem.

[0005] Recently, in an electron beam writing device which strict positional control is demanded, it is demanded to control the amount of magnetic variation from 0.3mG to 1mG or less. There is a need to give sufficient consideration to the environment where the device is installed.

[0006] As an installation room where such device is installed, generally, there has been adopted a so-called shield room, the wall surface of which is constructed with a high magnetic permeability material represented by Permalloy to thereby attenuate the magnetic variation therein occurring from the surrounding influence.

[0007] The method of attenuating the magnetic variation occurring from the surrounding influence by the above-described method, ordinarily, is called “a passive magnetic shield method”.

[0008] However, in the passive magnetic shield method, to satisfy the recent-year device requirements, it is necessary to increase the number of Permalloy layers or to increase the thickness of each layer. The actual circumstance therefore is that the relevant cost rapidly increases on a cumulative basis. This becomes an obstacle to decreasing the installation cost of the device.

[0009] Further, in a low-frequency range around 0.1 to 1.0 Hz, it is confirmed that the shielding performance is degraded and it is known that it is difficult to suppress the magnetic variation due to the passing-by of an automotive vehicle, etc efficiently.

[0010] Under the above-described existing circumstances, as a new type of shield room, in recent years, there has been developed a technique of applying a magnetic coil to a figuration (ordinarily the six surfaces of a rectangular parallele piped configuration) surrounding a space wanted to be magnetically shielded, detecting the magnetic variation occurring from the surrounding influence by an internal or an external magnetometric sensor, and controlling the electric current flowing through the electromagnetic coil so as to cancel that magnetic variation to thereby actively shielding the space.

[0011] The above-described method of actively attenuating the magnetic variation occurring from the surrounding influence is called “an active magnetic shielding method”.

[0012] However, there still is no method with a satisfying performance enough to displace the existing shielding room, and there remains the problem that the magnetic variation that especially comes from the neighborhood and so forth cannot be coped.

SUMMARY OF THE INVENTION

[0013] As described above, since there still is no method with a satisfying magnetic shielding performance enough to displace the existing shielding room and the magnetic variation that especially comes from the neighborhood cannot be coped. Therefore, for an electron beam control device which controls an electron beam for use, such as an electron microscope, an electron beam exposure device and the like, a device which a track of an electron beam is not adversely influenced by the amount of magnetic variation occurring from surrounding influences.

[0014] The present invention has been achieved in order to solve the above problems. It is an object of this invention to provide an electron beam control device which controls an electron beam for use, such as an electron microscope, an electron beam exposure device and the like where a track of an electron beam is not adversely influenced by the amount of magnetic variation occurring from surrounding influences.

[0015] In the electron beam control device of the present invention, it is an electron beam control device which controls an electron beam for use, such as an electron microscope, an electron beam exposure device and the like, where a magnetometric sensor for measuring the amount of magnetic variation occurring from the surrounding influences, which adversely influences a track of an electron beam is provided.

[0016] Furthermore, in the above mentioned electron beam control device, a function for adjusting an electron beam control system according to the measured amount of magnetic variation occurring from the surrounding influences is provided, where the amount of position fluctuation of an electron beam occurring due to the amount of magnetic variation is calculated and a position of an electron beam is corrected to a position where the amount of position fluctuation is cancelled.

[0017] Still more, in the above mentioned electron beam control device, a function for displaying such fact and/or stopping an electron beam manipulation, when the measured amount of magnetic variation occurring from the surrounding influences exceeds a predetermined range, is provided.

[0018] Incidentally, the electron beam control system here means an electron-optical system portion.

[0019] The electron beam control system of the present invention, by having the above-described construction, has enabled to provide an electron beam control device, such as an electron microscope and an electron beam exposure device, where a track of an electron beam is not adversely influenced by the amount of magnetic variation occurring from surrounding influences.

[0020] Shortly, a magnetometric sensor for measuring the amount of magnetic variation is provided in the electron beam control device to stop the electron beam manipulation, or to correct the position of the electron beam by adjusting the control system, according to the measured amount of magnetic variation. Thereby, it enables to control the influence of the magnetic variation.

[0021] By this, it is possible to control the positional variation of the electron beam due to the magnetic variation and to realize the electron beam position control with a high accuracy.

[0022] The present invention, as described above, has enabled providing an electron beam control device which controls an electron beam for use, such as an electron microscope, an electron beam exposure device and the like where a track of an electron beam is not adversely influenced by the amount of magnetic variation occurring from surrounding influences.

[0023] That is to say, it is possible to realize a high accuracy electron beam control device that is not influenced of the amount of magnetic variation occurring from the surrounding influences.

[0024] As a result of this, especially in the electron beam exposure device for use for the preparation of a photomask, while, with the increase in the density of the semiconductor device, with the proceeding miniaturization of the pattern of the photomask, in recent years, and the influence of the amount of magnetic variation occurring from the surrounding influences has been also becoming problematic in terms of the quality of the product, that exposure device can cope with such problem.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1 is a schematic construction diagram showing an embodiment of an electron beam control device of the present invention;

[0026]FIG. 2 is a chart showing the amount of magnetic variation occurring from the surrounding influences to the electron beam;

[0027]FIG. 3 is a chart showing the amount of positional variation of the electron beam that occurs when the magnetic variation shown in FIG. 2 has been applied; and

[0028]FIG. 4 is a chart showing the positional variation of the electron beam that occurs when the magnetic variation shown in FIG. 2 has been applied, in the case which the electron beam control device of the present invention has been used.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] An embodiment of an electron beam control device in the present invention will now be explained with reference to the drawings.

[0030]FIG. 1 is a schematic construction diagram showing an embodiment of the electron beam control device of the present invention.

[0031] In FIG. 1, a reference numeral 10 denotes an installation room (of an electron beam exposure device), a reference numeral 11 denotes a wall, a reference numeral 20 denotes an electron beam exposure portion, a reference numeral 21 denotes an electron-optical system portion (also called “a lens-barrel portion”), a reference numeral 22 denotes a bench (also called “a vibration-proof platform”), a reference numeral 25 denotes an electron beam controller, a reference numeral 30 denotes a magnetometric sensor, a reference numeral 31 denotes a wiring for the magnetometric sensor, and a reference numeral 32 denotes an amplifier.

[0032] The electron beam control device of this embodiment will now be explained with reference to FIG. 1.

[0033] The electron beam control device of this embodiment is an electron beam exposure device that performs writing exposure for preparing the pattern of a photomask. The magnetometric sensor 30 for measuring the amount of magnetic variation, occurring from surrounding influence which adversely influences a track of an electron beam, is equipped near the electron-optical system portion 21 of the electron beam exposure portion 20. Further, the electron beam control device has a function for stopping the operation of exposure writing of the electron beam, when the measured amount of magnetic variation from the surrounding influence exceeds a predetermined range.

[0034] The electron beam exposure device of the embodiment, although not shown in the figure, shortly saying, an electron beam is controlled and irradiated from the electron-optical system portion 21 onto the surface of the substrate for preparing a photomask, while the substrate for preparing a photomask is being moved, in a state where a substrate for preparing a photomask is set on a stage which is controlled to move in X and Y directions.

[0035] Incidentally, the stage (not shown in the figure) and the electron-optical system portion 21 are provided on the bench (the vibration-proof platform) 22.

[0036] In the electron beam exposure device of this embodiment, ordinarily, the electron beam of the electron-optical system portion 21 is controlled according to the instruction issued from the controller 25, and, simultaneously, the position of the stage which moves in the X and Y directions is controlled, by a laser interferometer. By doing so, the irradiating position control of the electron beam, on the substrate for preparing a photomask, is performed and exposure writing is performed. On the other hand, the magnetometric sensor 30 monitors the magnetic variation near it at all times, and thereby sends the status of magnetic variation to the amplifier 32 via the wiring 31 for the magnetometric sensor on a real-time basis.

[0037] In this embodiment, when the electron beam irradiating position on the substrate for preparing a photomask is controlled, by the electron beam control of the electron-optical system portion 21 and by position control of the stage, the controller 25 takes the output of the amplifier 32 in, and if the output of the amplifier 32 is outside of the set range, the controller 25 compulsively cuts off the write enable signal to make the exposure writing operation to being kept in a state of standby. If the output of the amplifier 32 is within the set range, the controller 25 does not cut off the write enable signal, so that the exposure writing operation is kept in a state of being able to execute.

[0038] In this way, in the electron beam exposure device of this embodiment, when the measured amount, of magnetic variation occurring from the surrounding influences, by the magnetometric sensor 30 exceeds a prescribed range, it is arranged that the operation of exposure writing of the electron beam is stopped.

[0039] Incidentally, the write enable signal is a control signal of the controller that indicates a state which the exposure writing operation can be executed and that is a control signal which is used in an ordinary electron beam exposure device.

[0040] As the magnetometric sensor 30, there are a semiconductor magnetometric sensor, optical fiber magnetometric sensor, and SQUID (Superconducting Quantum Interference Device) magnetometer (also called “a flux meter”) that detect the amount of magnetic variation, they are used according to the environmental characteristic and use purpose. In this embodiment, a primary-differential type SQUID magnetometer is used.

[0041] Incidentally, as a wide-band magnetometric sensor for detecting the amount of magnetic variation which can detect a magnetic-field fluctuation level of several Hz to 1KHz or more, for example, the one that is made by Magban Company is known.

[0042] The present invention is not limited to the above-described embodiment.

[0043] For example, there is an electron beam exposure device which is equipped with a magnetometric sensor as in the case of the above-described embodiment, has a function to adjust an electron beam control system (the electron-optical system portion 21) according to the measured amount of magnetic variation occurring from the surrounding influences by the magnetometric sensor, and calculates the amount of positional variation of the electron beam that occurs corresponding to the amount of magnetic variation to correct the position of the electron beam to the position where the positional variation can be canceled.

[0044] In this case, shortly saying, there is a construction wherein, the amount of deflection of the electron beam is corrected according to the output of the amplifier 32 of the magnetometric sensor 30.

[0045] As a result of this, exposure writing can be performed without stopping the electron beam exposure device and without being qualitatively influenced by the amount of the magnetic variation occurring from the surrounding influences.

EXAMPLES

[0046] Examples are shown below, and the present invention will further be explained.

[0047] Example

[0048] A magnetic variation shown in FIG. 2 was externally given to an electron beam, and positional variation of the electron beam, in a case which the electron beam was controlled by the electron beam control device shown in FIG. 1, was measured.

[0049] As the magnetic variation that is externally given, 0.15mG of variation was applied continuously for 180 seconds, thereafter that application was stopped (FIG. 2).

[0050] The measured result is shown in FIG. 4. The positional variation of the electron beam was 3σ=1.8nm.

[0051] Comparative Example

[0052] Except for that the electron beam control device shown in FIG. 1 was not used, the positional variation of the electron beam was measured under the same conditions as those in the Example 1 above.

[0053] As a result of the measurement, the positional variation of the electron beam was 3σ=4.7nm with respect to 0.15mG of magnetic variation. The measured result is shown in FIG. 3. In FIG. 3, it is obvious that the position of the electron beam is greatly curved in such a way as to be synchronized with the magnetic variation that has been applied.

[0054] From the both results of the Example and the Comparative Example, it is shown that when using the electron beam control device shown in FIG. 1, the amount of positional variation of the electron beam can be greatly improved.

[0055] The electron beam control device of the present invention is equipped with a magnetometric sensor so as to suppress the amount of positional variation of the electron beam, monitors the amount of magnetic variation occurring from surrounding influences at all times, and predicts the electron beam positional variation occurring from the magnetic variation. That electron beam control device, further, controls the electron beam to the position at which the positional variation is canceled, thereby eases the influence of the magnetic variation, and enables controlling the electron beam to a stable position as shown in FIG. 4. By using the electron beam control device of the present invention, electron beam can be controlled without being influenced by the magnetic variation occurring from the surrounding influences. 

What is claimed is:
 1. An electron beam control device which controls an electron beam for use, such as an electron microscope, an electron beam exposure device and the like, wherein a magnetometric sensor for measuring an amount of magnetic variation which influences a track of the electron beam, occurring from surrounding influences, is provided.
 2. The electron beam control device according to claim 1, wherein the electron beam control device is provided with a function for adjusting an electron beam control system according to the measured amount of magnetic variation occurring from the surrounding influences, calculates the amount of positional variation of the electron beam which may occur according to the amount of magnetic variation, and a position of the electron beam is corrected to a position where the amount of positional variation is cancelled.
 3. The electron beam control device according to claim 1, wherein the electron beam control device is provided with a function for displaying such a fact and/or stopping an electron beam manipulation, when the measured amount of magnetic variation occurring from the surrounding influences exceeds a predetermined range.
 4. The electron beam control device according to claim 2, wherein the electron beam control device is provided with a function for displaying such a fact and/or stopping an electron beam manipulation, when the measured amount of magnetic variation occurring from the surrounding influences exceeds a predetermined range. 